Recently, so-called MMORPG (Massively Multiplayer Online Role-Playing Game) for enjoying a role-playing game in a virtual space set in a game server with which many players are connected through a communication line is now widespread.
In many cases in the RPG (role-playing game), an operation character operated by a player runs various kinds of risks (does quests) according to a game scenario set in a game program (see patent related document 1 shown below). One of such quests can be attained only by clearing one scenario, and another quest is so-called succeeding quest wherein the whole quest can not be attained until two or more partial quests are cleared in a predetermined order.